Apparatus, system, and method for automated item tracking

ABSTRACT

Disclosed is an automated item tracking method, comprising the steps of reading an RFID signal, obtaining a reported position of an RFID signal generator, measuring the strength of the read RFID signal, creating a read profile, obtaining a physical package profile, comparing the read profile to the physical package profile, and generating a weighted read profile to estimate an actual position of the RFID signal generator by comparing the weighted read profile with the physical package profile.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/132,344, filed Dec. 4, 2009, which is a National Stage PatentApplication of International Application No. PCT/US2009/066797, filedDec. 4, 2009, which claims the benefit of U.S. Provisional PatentApplication No. 61/193,520, filed Dec. 4, 2008, each of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to Radio Frequency Identification, or RFIDtechnology, and more particularly to ways of correlating RFID data witha package traveling on a conveyor system or manufacturing line.

DISCUSSION OF THE RELATED ART

RFID readers are inherently inaccurate when it comes to determining anRFID signal generator position. RF read zone volumes are potentiallymuch larger than the volume of the package carrying the RFID tag. Thesystem can therefore read RFID tags from multiple packages within theread zone simultaneously or nearly simultaneously, without knowing wherein the zone each RFID tag was read. This makes matching the RFID datawith the correct package difficult, especially if multiple packageswithin an RF read zone are detected during the same read cycle.Therefore, while many systems collect RFID data, few can match the datato a physical item when there are multiple items with minimal spacingbetween them entering the system at high speeds.

Existing RFID methods of tracking and data correlation have manyshortcomings. For example, while existing systems can read RFID tags inan automated conveyor environment, these systems lack the ability tocorrelate the RF data with the packages reliably, particularly whenspacing is decreased. This prevents the system from helping the customerautomatically divert a desired package (a TV, for example) to thecorrect location. For example, two packages are moving down a conveyorsystem in a warehouse. The first package contains a television destinedfor a first store. The second package contains paper towels destined fora second store. The warehouse has an automated diverter located ten feetand six inches down the conveyor from an equipment location. A customerwants to divert the package with the television, but not the packagewith the paper towels. In certain scenarios, existing systems mistakenlyassociate the RFID data from the package with the TV with RFID data forthe package containing paper towels. The system then ships and bills thetelevision to the customer requesting paper towels, and ships and billsthe paper towels to the customer requesting the television. These errorsare expensive to correct.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus, system,and method for automated item tracking that substantially obviates oneor more problems due to limitations and disadvantages of the relatedart.

An object of the present invention is to provide a system that matchesRFID data with packages moving at high speeds on conveyor systems or onmanufacturing lines. This helps customers manage inventory by deliveringreliable and actionable data to the customer at specific points in timeor when a package reaches a specific location. Going back to theprevious example, to avoid incorrectly diverting the package with thetelevision, the system reads the RFID data on the package with thetelevision and creates a weighted map of the read profile (based onnumber of reads, time between reads, and the strength of the RF signal),matches that profile to the first package profile, and transmits thatdata once the leading edge of the package reaches a predeterminedposition down the belt. The data is typically transmitted to thecustomer diverter system that routes packages, another type ofautomation controller, and/or a software database. A customer uses thisdata to divert the television package to a desired location, whileleaving the package with the paper towels on the conveyor system.

Additional features and advantages of the invention will be set forth inthe following description, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, theapparatus, system, and method for automated item tracking includes anautomated item tracking method, comprising the steps of reading an RFIDsignal, obtaining a reported position of an RFID signal generator,measuring the strength of the read RFID signal, creating a read profile,obtaining a physical package profile, comparing the read profile to thephysical package profile, and generating a weighted read profile toestimate an actual position of the RFID signal generator by comparingthe weighted read profile with the physical package profile. RFID signalgenerator is a generic term that refers to an RFID tag, RFIDtransponder, printed RFID resonance device, or any other source of RFIDdata known to those skilled in the art.

In another aspect, an automated tracking system includes means forreading an RFID signal, means for obtaining a reported position of anRFID signal generator, means for measuring the strength of the read RFIDsignal, means for creating a read profile, means for obtaining aphysical package profile, means for comparing the read profile to thephysical package profile; and means for estimating an actual position ofthe RFID signal generator by comparing the weighted read profile withthe physical package profile.

In another embodiment, an automated item tracking system includes anRFID reader having an RF module, a processor, and an antenna, a packagedetector, a position indicator, and a processor, the processoroperatively connected to the RFID reader, package detector, and positionindicator.

Still another embodiment includes an automated item tracking systemcalibration method, comprising the steps of running a conveyor at astable and measurable speed, placing a package of known dimensions onthe conveyor, the package having an RFID signal generator in apredetermined position on the package, reading an RFID signal when theRFID signal generator is a known distance from an RFID reader,calculating a package position based on the read RFID signal, andcalculating an offset based on the difference between the known packageposition and the calculated package position.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is an exemplary block diagram showing an automated item trackerin accordance with the present invention;

FIG. 2 is an exemplary block diagram of an RFID reader in accordancewith the present invention;

FIG. 3 is an exemplary embodiment of an automated item tracker physicalconfiguration in accordance with the present invention; and

FIG. 4 illustrates an exemplary embodiment of raw and post-calibrationdata obtained from an automated item tracker in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 is an exemplary block diagram showing an automated item trackerin accordance with the present invention. As shown in FIG. 1, the systemcorrelates near-accurate data streams from multiple sources(tachometers, photo eyes, PLC data, in-motion scales, barcode readers,sort controllers, etc) and an inaccurate data stream (RFID readers),with a physical item traveling on a conveyor system. The system hasthree subsystem inputs—Subsystem A, Subsystem B, and Subsystem C, whichare described below. The system optionally includes a processingsubsystem (Subsystem D) that may be independent or combined withSubsystem A.

In the exemplary embodiment shown in FIG. 1, the processing subsystemuses RFID data from Subsystem A to create a weighted read profile, whichis created, in part, with signal strength hardware and RFID signalgenerator read counting software. The signal strength is gathered fromthe underlying hardware, and recorded for each valid read of the RFIDsignal generator. The weighted read profile is a software representationof the raw data obtained from the subsystems. Each time the RFID signalgenerator is read, the position obtained from Subsystem C (discussedbelow) is recorded, and the strength of the signal obtained from thehardware is recorded. All position and strength data associated with anindividual RFID signal generator are used to create a profile.Additionally, the first and last time an RFID signal generator is readand the number of times an individual RFID signal generator is read isused in the profile. This profile is compared to a physical packageprofile from Subsystem B (discussed below), and used to identify thelocation of the RFID signal generator in the physical world.

In the embodiment shown, Subsystem A is the RFID reader, also called aninterrogator, that facilitates a wireless communication with an RFIDsignal generator placed on an item the user wishes to identify, locate,or track. The RFID reader that makes up Subsystem A passes a continuousstream of RFID data, the time between reads, and the read signalstrength to the processing subsystem (Subsystem D). Subsystem A includesthe hardware needed to read RFID signal generators including, but notlimited to, an RF module, processor, and antenna. FIG. 2 is an exemplaryblock diagram of an RFID reader for use with Subsystem A.

In the embodiment shown in FIG. 1, Subsystem B is a photoeye signalgenerator. The photoeye uses beam-breaking detection to indicate thepresence or absence of an object. The photoeye signal generator isexemplary only, and not limited to what is shown. This signal fromSubsystem B could also be generated from a camera system, a structuredlight patterns system (height delta detecting systems), or other systemknown to those skilled in the art that provides a representation of thephysical items to be tracked.

In the embodiment shown in FIG. 1, Subsystem C is a timing/positionsystem. Any speed/position sensor can be used, such as a pulse positionindicator, an artificially generated pulse train representative ofconveyor speed/position (for example a signal generated by aprogrammable logic controller), or other devices for conveyor orassembly line control known to those skilled in the art.

FIG. 4 illustrates the data streams and an exemplary method ofcalibrating the system shown in FIG. 3. During system setup of thesystem shown in FIG. 3, a specific calibration process is used to learnthe physical environment. A sample package with an RFID signal generatorthat is placed in the exact middle of the package side facing the RFIDread antenna is placed on the conveyor running at a desired speed, andthe sample package is run through the system multiple times. Datarecorded from Subsystems A-C is recorded by the processing subsystem(Subsystem D). The processing subsystem then averages the data andstores parameters representing the offsets between each subsystem. Theseoffsets can be thought of as mapping parameters that the system uses tomap the three subsystems to a common coordinate system. For example,assume a pulse position indicator (Subsystem C) is used that offersresolution of four pulses per inch. Additionally, assume the photoeye(Subsystem B) is physically mounted two inches in front of the leadingedge of the RFID antenna. Finally, assume the RFID antenna in SubsystemA is a six-inch square antenna. Because each antenna and environment mayproduce a different RF field that has the potential to read RFID signalgenerators at different locations, the system must “learn” where thecenter of the RF field is. This is the purpose of the calibration. Thesystem would also evaluate the start and end pulse where RFID signalgenerators were read and the signal level at each of those points. Inthe present example, suppose the sample RFID signal generators in thecalibration run are placed on the center of a 4″ long box and showmaximum read rate, and highest signal level 34 pulses from the firstinstance the photoeye beam was broken, on average. Additionally, assumethe first read occurred at 18 pulses and the last read at 50 pulses.Subsystem B would indicate the box in our example was 16 pulses longstarting at pulse 6 and ending at pulse 22. Using this information, theprocessing subsystem would conclude that the center of the RFID readfield is 20 pulses past the center of the box as indicated by the datastream from Subsystem B, or 5″, in our example. The processing subsystem(Subsystem D) would use the offset to shift all future photoeye data by20 pulses to match the data from Subsystem A with that of Subsystem B.

In another embodiment of the invention, the system generates aconfidence factor that indicates the reliability of the informationpassed to an upstream device (e.g., a customer PLC, a server, etc). Thisgoes beyond a simple “quality of read indicator”, by also incorporatingthe reliability of the correlation of the RFID signal generator with thephysical item. Subsystems A-C work together to gauge the likelihood thataccurate information was obtained from each subsystem, and estimate thelikelihood that the data has been matched correctly. Exemplaryembodiments of input Subsystems A-C and the processing subsystem(Subsystem D) are discussed below.

Subsystem A is an RFID reader that feeds signal strength, and RFID readdata and RFID read data timing to the processing subsystem (Subsystem D)in order to build a weighted read profile. The signal strength hardwareis part of an RFID radio and provides an indication of the signalstrength of the RFID signal generator signal as received at the reader.The signal strength is most often affected by RFID signal generatororientation in relation to a reader's antenna and the RFID signalgenerator's distance from the antenna. Signal strength can also beaffected by overall system power and RFID signal generator quality.Signal strength and RFID signal generator quality vary by system set up,but then remain constant. RFID readers can operate at different powerand RFID signal generators of different size will produce differentsignal strength, but once a system is set up, the signal strength due tothese factors should not vary. Readers are designed to a certainspecification and this causes signal strength due to system power andRFID signal generator quality to be known at time of manufacture and theexpected strength value to be stable and constant for a given productmodel. In other words, once a reader's power is set and/or an RFIDsignal generator of particular size is chosen, the signal strengthproduced is expected to be constant. Now, by varying the RFID signalgenerator orientation and/or distance, a relative change in signalstrength can be measured. The farther away the RFID signal generator isfrom the antenna, the lower the signal strength. An RFID signalgenerator produces maximum signal strength when it is in a planeparallel to the reader's antenna plane. Signal strength is minimizedwhen the RFID signal generator is in a plane orthogonal to the readerantenna and the signal strength varies at angles in between. The systemuses relative changes in signal strength to gather information about howwell it is communicating with a given RFID signal generator. The RFIDdata and RF signal strength are inherently associated with the weightedread profile, since the read data and the signal strength are gatheredat the same time as the reading occurs. Higher signal strength and anincrease in the number of times an RFID signal generator is read in agiven time period are directly correlated with a better quality transferof data between the reader and RFID signal generator.

Subsystem B is a generic package detection device, such as a simpleoptical package detector (photo-eye), or possibly a more sophisticatedheight change detection system (camera, light curtain, etc). Thesubsystem applies filters to the data to eliminate system noise andsignals that do not fall within package parameter data. In the presentembodiment, the filters are comparators that pass data along to the nextstage if the package parameter data is greater than a low threshold andless than a high threshold. Data not meeting these criteria arediscarded. For instance, a system may expect boxes that are betweenapproximately 4″ long and approximately 36″ long. The filter willeliminate inputs falling outside of this range. These eliminated inputscan be caused by, for example, loose debris in the system, or boxesoutside the desired parameters that are inadvertently placed in thesystem.

Subsystem C of this exemplary embodiment is a generic beltspeed/position indication square wave, such as what is generated by apulse position indicator or artificial signal from a programmable logiccontroller that is indicative of the automated system speed.

The processing subsystem (Subsystem D) collects data from eachsubsystem. The module collects data using, for example, software driversor other collection modules known to those skilled in the art. The datafrom Subsystems A-C is then correlated. Subsystems B and C have defineddata streams, and are correlated through simple calibration offsets. Forexample, Subsystem C may produce an electrical pulse for each inch ofconveyor belt travel. So four pulses occurring in one second wouldequate to a belt speed of 4″ per second. Subsystem B may be a photoeyeand typically will exhibit a change of electrical state when a boxtraveling on the conveyor first breaks its beam path. It will thenreturn to its original state once the box exits the beam path. SubsystemA is correlated to Subsystems B and C by comparing the weighted readprofile of Subsystem A with the carton profile map of Subsystems B andC.

The system then generates an output rating that increases as confidencein the correlation increases. The confidence in the correlation ratingincreases proportionally to how well the weighted read profile matchesthe package profile. The output rating is represented as, for example, atwo digit percentage from 0 to 100. Factors that increase the confidenceinclude, but are not limited to: (1) increased package spacing, (2) ahigh RFID signal strength, (3) multiple reads of the same RFID data, (4)a consistent Subsystem C data rate indicative of a constant rate oftravel through the subsystems, and (5) relatively little filtering ofdata from Subsystem B inputs. Increased package spacing decreases thelikelihood of two Subsystem A profiles overlapping data from SubsystemsB and C. High RFID signal strength and an increase in RFID data reads ina given period of time increases the likelihood the RFID signalgenerator and reader are communicating well and that the RFID signalgenerator is directly in front of Subsystem A. Having the RFID signalgenerator directly in front of the Subsystem A antenna maximizes theadvantage of the calibration procedure and the correlation of dataprofiles from the different subsystems. Consistent data from Subsystem Cindicates the item to be detected is moving through the system at anorderly rate of speed. If the item were to stop and start or changespeed rapidly, the calibration factors become less effective because therelationships between the subsystems become non-linear. An increase infiltering of data from Subsystem B has the potential to distort the itemprofile from that subsystem. Input data that does not need to befiltered increases the likelihood that the Subsystem B profile isaccurate. Other factors may be considered without departing from thescope of the invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the apparatus, system, andmethod for automated item tracking without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioncover the modifications and variations of this invention provided theycome within the scope of the appended claims and their equivalents.

What is claimed is:
 1. An automated item tracking method, comprising thesteps of: reading an RFID signal associated with an item; obtaining areported position of the item; measuring the strength of the read RFIDsignal; creating a read profile; obtaining a physical package profile ofthe item; comparing the read profile to the physical package profile;generating a weighted read profile of the item; and estimating an actualposition of the item by comparing the weighted read profile with thephysical package profile.
 2. The automated item tracking method of claim1, wherein the reported position of the item is obtained using anoptical package detector.
 3. The automated item tracking method of claim1 further comprising the step of: discarding a data reading that fallsoutside the physical package profile.
 4. The automated item trackingmethod of claim 3 further comprising the step of: counting the number ofdiscarded data readings.
 5. The automated item tracking method of claim1 further comprising the step of: recording the first time, the lasttime, and the total number of times an RFID signal is read.
 6. Theautomated item tracking method of claim 1 further comprising the stepof: generating a confidence factor, wherein the confidence factorincreases as the difference between the weighted read profile and thephysical package profile decreases.
 7. The automated tracking method ofclaim 1, wherein the reported position of the item is obtained using atachometer.
 8. The automated tracking method of claim 1, wherein thereported position of the item is obtained using a barcode reader.
 9. Theautomated tracking method of claim 1, wherein the reported position ofthe item is obtained using an in-motion scale.
 10. The automatedtracking method of claim 1, wherein the reported position of the item isobtained using a camera system.
 11. The automated tracking method ofclaim 1, wherein the reported position of the item is obtained using astructured light patterns system.
 12. The automated tracking method ofclaim 1, wherein the reported position of the item is obtained using adimension detection system.
 13. The automated tracking method of claim 1further comprising: routing the item along a travel path based on anidentity of the item and the estimated actual position of the item. 14.An automated item tracking system, comprising: means for reading an RFIDsignal associated with an item; means for obtaining a reported positionof the item; means for measuring the strength of the read RFID signal;means for creating a read profile; means for obtaining a physicalpackage profile of the item; means for comparing the read profile to thephysical package profile; means for generating a weighted read profileof the item; and means for estimating an actual position of the item bycomparing the weighted read profile with the physical package profile.15. An automated item tracking system calibration method, comprising thesteps of: running a conveyor at a measurable speed; placing a package onthe conveyor, the package having an RFID signal generator on thepackage; reading an RFID signal repeatedly and recording the change indistance of the RFID signal generator; calculating a package positionbased on the read RFID signal; and calculating an offset based on thedifference between a known package position and the calculated packageposition.